The present invention relates to video image processing, and in particular to an apparatus and method for interpolating a pixel within an image arranged as an array of pixels.
Analog television signals contain fields transmitted in temporal succession, wherein the fields are constructed linewise. A field comprising the even-numbered lines and a field comprising the odd-numbered lines are transmitted alternately.
A variety of methods are known for generating a frame from such a field. In the simplest case, the lines of the field are duplicated so that the items of video information of the pixels of an intermediate line between two lines of a field are specified by the video information values of the image line lying above the intermediate line or below the intermediate line. In this procedure, however, in which adjacent lines are identical two by two, edges running diagonally in the image have a graduated or stairstep appearance.
In another known method, the video information value associated with a pixel of an intermediate line is determined by taking the average of the video information values of the pixels lying vertically above and vertically below the pixel to be interpolated and selecting the average as the video information value of the pixel of the intermediate line. This method has the disadvantage that vertical edges have an indistinct appearance because of the insertion of a line containing the averages.
Therefore, there is a need for a pixel interpolation apparatus and method that is simple to implement and is not constrained by the above-cited disadvantages.